Referring to FIG. 1, a conventional EL display device includes an EL display panel 2 and a driving circuit. The driving circuit comprises a controller 21, a scanning driving unit 6, and a data driving unit 5. The EL display panel 2 has a plurality of data electrode lines 3 and scanning electrode lines 4 intersecting each other at a predetermined distance. The EL display panel 2 further has electro-luminescence cells 1, each being formed at the intersections between the data electrode lines 3 and the scanning electrode lines 4.
The controller 21 receives and processes image signals SIM. The processing includes applying data control signals SDA and scanning control signals SSC to the data driving unit 5 and the scanning driving unit 6, respectively. The data control signals SDA include the display data signals and the switching control signals, while the scanning control signals SSC are the switching control signals.
The data driving unit 5 connected to the signal-input terminals of the data electrode lines 3 produces data current signals, corresponding to the display data signals from the controller 21 in response to the switching control signals received from the controller 21, and applies the data current signals to the data electrode lines 3. Here, reference number 8 denotes current sources.
The scanning driving unit 6 connected to the signal-input terminals of the scanning electrode lines 4 sequentially applies scanning driving signals, in response to the switching control signals received from the controller 21, to the scanning electrode lines 4.
Referring to FIG. 1 and FIG. 2, the data driving unit 5 of the EL display device of FIG. 1 includes an interface 30, a latch circuit 31, digital-to-analog (D/A) converters 32, and an output circuit 33.
The latch circuit 31, operating according to a horizontal synchronization signal HSYNC received from the controller 21 through the interface 30, periodically stores the display data signals DDA received from the controller 21 through the interface 30 while periodically outputting display data signals in the current and next horizontal drive time periods, respectively. Each of the D/A converters 32 converts each of the display data signals in the current horizontal drive time period received from the latch circuit 31 into a data current signal. The output circuit 33 then applies data output signals ID1-IDm, corresponding to the display data signals received from the D/A converters 32, to the corresponding data electrode lines 3, respectively.
As an example of a conventional EL display device configured as above, U.S. Pat. No. 6,531,827 discloses a technology for improving driving speed by applying booting current at the beginning of each horizontal drive time period. European Laid-open Patent Publication No. 1,091,340 proposes a technology for reducing power consumption by controlling the booting current according to a change in the amount of data. A conventional driving apparatus and method using the above-cited technologies will now be described.
Referring to FIGS. 1, 2 and 3, the latch circuit 31 of the data driving unit 5 of FIG. 2 generally comprises (n+1)-data registers 31R1-31Rm and n-data latches 31L1-31Lm. The output circuit 33 of the data driving unit 5 includes digital comparators 33C1-33Cm, D/A converters 33D1-33Dm, and output current switches S1-Sm.
Each of the (n+1)-data registers 31R1-31Rm outputs a display data signal stored therein according to the horizontal synchronization signal HSYNC and stores a display data signal Dn+1 received from the controller 21 through the interface 30. The n-data latches 31L1-31Lm output display data signals stored therein in response to the horizontal synchronization signal HSYNC and store the display data signals Dn received from the (n+1)-data registers 31R1-31Rm, respectively. The D/A converters 321-32m then convert the display data signals Dn in the current horizontal drive time period received from the n-data latches 31L1-31Lm into data current signals IDP1-IDPm, respectively.
The digital comparators 33C1-33Cm of the output circuit 33 compare the display data signals Dn in the current horizontal drive time period received from n-data latches 31L1-31Lm with the display data signals Dn+1 in the next horizontal drive time period received from (n+1)-data registers 31R1-31Rm, respectively. The digital comparators 33C1-33Cm generate booting data signals according to the comparison results. The D/A converters 33D1-33Dm convert the booting data signals received from the digital comparators 33C1-33Cm into analog signals and output booting current signals IB1-IBm, respectively. The output current switches S1-Sm apply data output signals ID1-IDm to the data electrode lines 3, respectively. The data output signals ID1-IDm are generated by alternately selecting the output signals IB1-IBm of the D/A converters 33D1-33Dm of the output circuit 33 or output signals IDP1-IDPm of the D/A converters 321-32m, respectively.
A method for driving a conventional EL display device having a data driving unit 5 as shown in FIG. 3 will now be described with reference to FIGS. 3 and 4. In FIG. 4, reference character IDP1 is a data current signal from D/A converter 321, ID1 is a data output signal applied to the data electrode line (3a of FIG. 1) from the output current switch S1 corresponding to the D/A converter 321, VD1 is a data voltage signal applied to the data electrode line 3a, and VS1-VS6 are scanning voltage signals applied to the scanning electrode lines (4 of FIG. 1).
With reference to the data output signal ID1, a booting current corresponds to a magnitude change of a display data signal Dn+1 in a next horizontal drive time period with respect to a display data signal Dn in a current horizontal drive time period. The booting current is applied to the data electrode line 3a at the beginning of the next horizontal drive time period. An instantaneous value of the booting current is proportional to a magnitude change of the data current signal IDP1. In connection therewith, first and second drive periods t1˜t3 and t3˜t5 will now be representatively described.
The magnitude of the data current signal IDPI at the scanning time interval t2˜t3 increases over that of the data current signal IDP1 at the previous scanning time interval (not shown) during booting time interval t1˜t2 of the first horizontal drive period t1˜t3. A positive polarity booting current, proportional to the amount by which the magnitude of the data current signal IDP1 at the scanning time interval t2˜t3 increases from the previous scanning time interval, is applied to the data electrode line 3a. 
Conversely, the magnitude of the data current signal IDP1 at scanning time interval t4˜t5 decreases over that of the data current signal IDP1 at the previous scanning time interval t2˜t3 during booting time interval t3˜t4 of the second horizontal drive period t3˜t5. A negative polarity booting current, proportional to the amount by which the magnitude of the data current signal IDP1 at the scanning time interval t4˜t5 decreases from the previous scanning time interval t2˜t3, is applied to the data electrode line 3a. 
Thus, the typical driving apparatus and method can improve the driving speed using the booting current. However, since the instantaneous value of booting current are proportional to the magnitude change of the data current signal IDP1, the instantaneous value of booting current may increase significantly when the change becomes very large. This may cause crosstalk such that EL cells that are not scanned glow, as well as increase power consumption.